The invention relates generally to a vortex tube used to provide cooling for air or gas drilling operations.
A vortex tube is a mechanical device that can be used to separate gas streams into a hot stream and a cold stream. The separation of the hot stream from the cold stream is accomplished by first expanding the gas stream at the inlet of the vortex tube. Then the gas stream then enters a swirl chamber with a high tangential velocity and is forced to travel towards a hot end of the vortex tube. When traveling towards the hot end of the vortex tube, the gas stream is separated into an outer hot stream and an inner cold stream. Lastly, a valve placed at the hot end of the vortex tube directs the hot stream and the cold stream.
Vortex tubes are characterized as either a downstream type or a counter flow type. In the downstream type, the valve allows both the hot stream and the cold stream to exit out the hot end of the vortex tube. Alternatively, in the counter flow type, the valve directs the cold stream in the opposite direction where it exits the vortex tube out of a cold end and directs the hot stream to exit out of the hot end of the vortex tube.
The use of air or gas streams as circulating mediums for drilling operations in recovery wells, including oil, natural gas, and geothermal fluids wells, has become a widely accepted and effective technique in recovery operations. In some instances, “air drilling” or “gas drilling” with compressed air or nitrogen is a preferred approach over conventional heavy drilling fluids, which are used, for instance, in drilling oil wells.
Heavy drilling fluids are used to cool drilling bits and bring broken rock cuttings up to the surface of the well. However, in addition to being expensive, the heavy drilling fluids exert high pressure on the rocks, which reduces drilling rates. For shallow and dry formations of the well, air drilling or gas drilling is a more economical approach that can speed up the drilling process considerably.
Commonly, the compressed air or gas is pumped into a drilling string of a drilling rig and utilized directly in the drilling process. In such operations, however, high amounts of heat are generated at the drilling bits deployed within the well. The drilling bits and other equipment exposed within the well tend to deteriorate under the high heat stress by cracking and burning over time. When such drilling tools deteriorate, they require replacements, which can be frequent and result in costly idling time.
Therefore, it would be desirable to have a vortex tube capable of providing adequate cooling to an air or gas drilling operation. Furthermore, it would be desirable to have a cooling system comprising a plurality of vortex tubes capable of meeting high flow capacity demands present in air or gas drilling operations.